This paper presents a general search method to speed up the encoding process for vector quantization. The method exploits the topological structure of the codebook to dynamically eliminate the code vectors for encoding a particular input vector and thus decrease the number of distance calculations which require very intensive computations. The relations between the proposed method and several exis...
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A new approach to detection and correction of transmission errors in DPCM images is proposed. Here each transmission error (streak noise) is detected via a sequence of the Wilcoxon-Mann-Whitney (WMW) rank-sum tests performed on a sliding window using four particularly designed grouping schemes. Instead of four possible patterns used by Kundu and Wu (1990), in the proposed approach 18 possible dete...
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Switched-capacitor technology implemented by 2.4 μm CMOS offers considerable reliability/cost advantages. Its limited clock-rate values are the traditional obstacle to its introduction in high frequency applications, such as video. This obstacle can be removed by an architectural scheme broadening the internal clock rate by an integer factor with respect to the input clock rate. The feasibility...
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The Cheops Imaging System is a compact, modular platform for acquisition, processing, and display of digital video sequences and model-based representations of moving scenes, and is intended as both a laboratory tool and a prototype architecture for future programmable video decoders. Rather than using a large number of general-purpose processors and dividing up image processing tasks spatially, C...
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This paper discusses the design of a combined DCT/IDCT CMOS integrated circuit for real time processing of HDTV signals. The processor operates on 8×8 blocks. Inputs include the blocked pixels that are scanned one pixel at a time, and external control signals that control the forward or inverse modes of operation. Input pixels have a precision of 9-b for the DCT and 12-b for the IDCT. The la...
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A new image coding system, termed directional classified gain-shape vector quantization (DCGSVQ), is introduced in this paper. A content-classifier, operating in the spatial domain, is employed to classify each image block of 8×8 pixels into one of several classes which represent various image patterns (edges in various directions, monotone areas, complex texture, etc.). Then a classified ga...
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One drawback of the discrete cosine transform (DCT) is visible block boundaries due to coarse quantization of the coefficients. Most restoration techniques for the removing blocking effect are variations of low-pass filtering, and as such, result in unnecessary blurring. The authors propose a new approach for reducing the blocking effect which can be applied to conventional transform coding withou...
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An optimal shortest word length implementation of the fast transform based upon mathematical analysis is presented. The flow graph of any fast transform can be expressed as the product of several sparse matrices, where each matrix represents a single pass butterfly operation (i.e., multiplication and accumulation). Each decomposed sparse matrix is analyzed to determine whether a butterfly operatio...
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Many image display devices can allow only a limited number of colors, called color palette, to be simultaneously displayed. In order to have a faithful color reproduction of an image, the associated color palette must be suitably designed. This paper presents a dependent scalar quantization algorithm to design the color palette effectively. The dependent scalar quantization algorithm consists of t...
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Two methods for bit-rate reduction of two-layer video codecs, without impairing their robustness to cell loss are introduced. Both methods employ an H.261 compatible coder at the base layer and an interframe coder at the second layer. In the first method a second H.261 is used to code the residual errors of input pixels. Parameters of this Twin-H.261 codec in terms of effect of motion estimation, ...
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A new systolic array without matrix transposition hardware is proposed to compute the two-dimensional discrete cosine transform (2-D DCT) based on the row-column decomposition. This architecture uses N2 multipliers to evaluate N×N-point DCTs at a rate of one complete transform per N clock cycles, where N is even. It possesses the features of regularity and modularity, and is thus ...
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A clustering algorithm for the design of efficient vector quantizers to be followed by entropy coding is proposed. The algorithm, called entropy-constrained pairwise nearest neighbor (ECPNN), designs codebooks by merging the pair of Voronoi regions which gives the least increase in distortion for a given decrease in entropy. The algorithm can be used as an alternative to the entropy-constrained ve...
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Huffman coding, a variable-length entropy coding scheme, is an integral component of international standards on image and video compression including high-definition television (HDTV). The high-bandwidth HDTV systems of data rate in excess of 100 Mpixels/s presents a challenge for designing a fast and economic circuit for intrinsically sequential Huffman decoding operations. This paper presents an...
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